Multi-hop teleportation in a quantum network based on mesh topology

In this paper, we propose a mesh-topology-based multi-hop teleportation scheme for a quantum network. By using the proposed scheme, quantum communication can be realized between two arbitrary nodes, even when they do not share a direct quantum channel. Einstein–Podolsky–Rosen pairs are used as quantum channels. The source node (initial sender) and all intermediate nodes make Bell measurements independently. They send the results to the destination node (final receiver) by classical channels. The quantum state can be determined from the Bell measurement result, and only the destination node is required for simple unitary transformation. This method of simultaneous measurement contributes significantly to quantum network by reducing the hop-by-hop transmission delay.     

Bidirectional Teleportation Protocol in Quantum Wireless Multi-hop Network

We propose a bidirectional quantum teleportation protocol based on a composite GHZ-Bell state. In this protocol, the composite GHZ-Bell state channel is transformed into two-Bell state channel through gate operations and single qubit measurements. The channel transformation will lead to different kinds of quantum channel states, so a method is proposed to help determine the unitary matrices effectively under different quantum channels. Furthermore, we discuss the bidirectional teleportation protocol in the quantum wireless multi-hop network. This paper is aimed to provide a bidirectional teleportation protocol and study the bidirectional multi-hop teleportation in the quantum wireless communication network.     

Multi-hop teleportation based on W state and EPR pairs

Multi-hop teleportation has significant value due to long-distance delivery of quantum information. Many studies about multi-hop teleportation are based on Bell pairs, partially entangled pairs or W state. The possibility of multi-hop teleportation constituted by partially entangled pairs relates to the number of nodes. The possibility of multi-hop teleportation constituted by double W states is (4/9)~n after n-hop teleportation. In this paper, a multi-hop teleportation scheme based on W state and EPR pairs is presented and proved. The successful possibility of quantum information transmitted hop by hop through intermediate nodes is deduced. The possibility of successful transmission is (2/3)~n after n-hop teleportation.     

Routing protocol for wireless quantum multi-hop mesh backbone network based on partially entangled GHZ state

Quantum multi-hop teleportation is important in the field of quantum communication. In this study, we propose a quantum multi-hop communication model and a quantum routing protocol with multihop teleportation for wireless mesh backbone networks. Based on an analysis of quantum multi-hop protocols, a partially entangled Greenberger–Horne–Zeilinger (GHZ) state is selected as the quantum channel for the proposed protocol. Both quantum and classical wireless channels exist between two neighboring nodes along the route. With the proposed routing protocol, quantum information can be transmitted hop by hop from the source node to the destination node. Based on multi-hop teleportation based on the partially entangled GHZ state, a quantum route established with the minimum number of hops. The difference between our routing protocol and the classical one is that in the former, the processes used to find a quantum route and establish quantum channel entanglement occur simultaneously. The Bell state measurement results of each hop are piggybacked to quantum route finding information. This method reduces the total number of packets and the magnitude of air interface delay. The deduction of the establishment of a quantum channel between source and destination is also presented here. The final success probability of quantum multi-hop teleportation in wireless mesh backbone networks was simulated and analyzed. Our research shows that quantum multi-hop teleportation in wireless mesh backbone networks through a partially entangled GHZ state is feasible.     

基于非对称量子通道受控QOT量子投票协议

提出一种量子投票协议, 协议基于非对称量子通道受控量子局域幺正操作隐形传输(quantum operation teleportation, QOT). 由公正机构CA提供的零知识证明的量子身份认证, 保证选民身份认证的匿名性. 计票机构Bob制造高维Greenberger-Horne-Zeilinger 纠缠态建立一个高维量子通信信道. 选民对低维的量子选票进行局域幺正操作的量子投票, 是通过非对称基的测量和监票机构Charlie的辅助测量隐形传输的. Bob在Charlie帮助下可以通过幺正操作结果得到投票结果. 与其他一般的QOT量子投票协议相比, 该协议利用量子信息与传输的量子信道不同维, 使单粒子信息不能被窃取、防止伪造.选举过程由于有Charlie的监督, 使得投票公正和不可抵赖.由于量子局域幺正操作隐形传输的成功概率是1, 使量子投票的可靠性得以保证. 关键词： 量子投票 高维GHZ纠缠态 非对称基测量 量子操作隐形传输     

Partially entangled states bridge in quantum teleportation

The traditional method for information transfer in a quantum communication system using partially entangled state resource is quantum distillation or direct teleportation. In order to reduce the waiting time cost in hop-by-hop transmission and execute independently in each node, we propose a quantum bridging method with partially entangled states to teleport quantum states from source node to destination node. We also prove that the designed specific quantum bridging circuit is feasible for partially entangled states teleportation across multiple intermediate nodes. Compared to two traditional ways, our partially entanglement quantum bridging method uses simpler logic gates, has better security, and can be used in less quantum resource situation.     

Multiple teleportation via partially entangled GHZ state

Quantum teleportation is important for quantum communication. We propose a protocol that uses a partially entangled Greenberger–Horne–Zeilinger (GHZ) state for single hop teleportation. Quantum teleportation will succeed if the sender makes a Bell state measurement, and the receiver performs the Hadamard gate operation, applies appropriate Pauli operators, introduces an auxiliary particle, and applies the corresponding unitary matrix to recover the transmitted state.We also present a protocol to realize multiple teleportation of partially entangled GHZ state without an auxiliary particle. We show that the success probability of the teleportation is always 0 when the number of teleportations is odd. In order to improve the success probability of a multihop, we introduce the method used in our single hop teleportation, thus proposing a multiple teleportation protocol using auxiliary particles and a unitary matrix. The final success probability is shown to be improved significantly for the method without auxiliary particles for both an odd or even number of teleportations.     

Two-qubit entangled state teleportation via optimal POVM and partially entangled GHZ state

Quantum teleportation is of significant meaning in quantum information. In this paper, we study the probabilistic teleportation of a two-qubit entangled state via a partially entangled Greenberger- Horne-Zeilinger (GHZ) state when the quantum channel information is only available to the sender. We formulate it as an unambiguous state discrimination problem and derive exact optimal positive-operator valued measure (POVM) operators for maximizing the probability of unambiguous discrimination. Only one three-qubit POVM for the sender, one two-qubit unitary operation for the receiver, and two cbits for outcome notification are required in this scheme. The unitary operation is given in the form of a concise formula, and the fidelity is calculated. The scheme is further extended to more general case for transmitting a two-qubit entangled state prepared in arbitrary form. We show this scheme is flexible and applicable in the hop-by-hop teleportation situation.     

多跳噪声量子纠缠信道特性及最佳中继协议

在量子通信网络中, 最佳中继路径的计算与选择策略是影响网络性能的关键因素. 针对噪声背景下量子隐形传态网络中的中继路径选择问题, 本文首先研究了相位阻尼信道及振幅阻尼信道上的纠缠交换过程, 通过理论推导给出了两种多跳纠缠交换信道上的纠缠保真度与路径等效阻尼系数. 在此基础上提出以路径等效阻尼系数为准则的隐形传态网络最佳中继协议, 并给出了邻居发现、量子链路噪声参数测量、量子链路状态信息传递、中继路径计算与纠缠资源预留等工作的具体过程. 理论分析与性能仿真结果表明, 相比于现有的量子网络路径选择策略, 本文方法能获得更小的路径平均等效阻尼系数及更高的隐形传态保真度. 此外, 通过分析链路纠缠资源数量对协议性能的影响, 说明在进行量子通信网设计时, 可以根据网络的规模及用户的需求合理配置链路纠缠资源.     

三能级单量子态控制双向量子隐形传态

采用张量表示和广义三维贝尔基测量的方法,提出了实现三能级单量子态控制双向量子隐形传态的协议.协议中,控制者Carol的量子态为任意广义三维贝尔基.选择六粒子纠缠态作为量子通道,并给出了判断任意六粒子纠缠态能否作为量子通道的必要条件.基于该条件,借助SO(3)群元素的幺正性,选择其任意两个元素作为幺正矩阵,给出了构建量子通道的一般方法.列举了两个具体构建量子通道的例子,其中Alice、Bob、Carol共同作用,进行相应的广义三维贝尔基测量和对应的幺正变换,最终实现了Alice和Bob之间量子态的交换,从而验证了所提协议的可行性.     

Distributed wireless quantum communication networks with partially entangled pairs

Wireless quantum communication networks transfer quantum state by teleportation. Existing research focuses on maximal entangled pairs. In this paper, we analyse the distributed wireless quantum communication networks with partially entangled pairs. A quantum routing scheme with multi-hop teleportation is proposed. With the proposed scheme, is not necessary for the quantum path to be consistent with the classical path. The quantum path and its associated classical path are established in a distributed way. Direct multi-hop teleportation is conducted on the selected path to transfer a quantum state from the source to the destination. Based on the feature of multi-hop teleportation using partially entangled pairs, if the node number of the quantum path is even, the destination node will add another teleportation at itself. We simulated the performance of distributed wireless quantum communication networks with a partially entangled state. The probability of transferring the quantum state successfully is statistically analyzed. Our work shows that multi-hop teleportation on distributed wireless quantum networks with partially entangled pairs is feasible.     

Distributed wireless quantum communication networks

The distributed wireless quantum communication network （DWQCN） ha~ a distributed network topology and trans- mits information by quantum states. In this paper, we present the concept of the DWQCN and propose a system scheme to transfer quantum states in the DWQCN. The system scheme for transmitting information between any two nodes in the DWQCN includes a routing protocol and a scheme for transferring quantum states. The routing protocol is on-demand and the routing metric is selected based on the number of entangled particle pairs. After setting up a route, quantum tele- portation and entanglement swapping are used for transferring quantum states. Entanglement swapping is achieved along with the process of routing set up and the acknowledgment packet transmission. The measurement results of each entan- glement swapping are piggybacked with route reply packets or acknowledgment packets. After entanglement swapping, a direct quantum link between source and destination is set up and quantum states are transferred by quantum teleportation. Adopting this scheme, the measurement results of entanglement swapping do not need to be transmitted specially, which decreases the wireless transmission cost and transmission delay.     

Faithful Multihop Two-Qubit Transmission Through GHZ-GHZ Channel

Quantum teleportation is an important method for transmitting quantum states between two quantum communication nodes. In this paper, we propose a low-latency quantum communication scheme based on Greenberger-Horne-Zeilinger (GHZ) state. To implement two-qubit transmission, the source and all intermediate nodes perform quantum measurements simultaneously and the measurement results are transmitted to the destination node through classical channel independently. The destination node performs appropriate unitary operation on its particles to recover the original two-qubit state based on received measurement results. Our scheme effectively reduces the end-to-end quantum communication delay.

     

Optimal Schemes for Quantum Teleportation of Ten-Qubit State

A teleportation protocol for certain class of ten-qubit state by utilizing an eight-qubit entangled state as a quantum channel has been proposed. In this paper, we present an optimal scheme for the teleportation of a ten-qubit state by using a stochastic local operation and classical communication(SLOCC) equivalent to four-qubit χ state as entanglement channel. Only von Neumann type measurement, controlled-not (CNOT) operations and appropriate unitary operations are needed in this scheme. Receiver Bob can reconstruct the initial state by introducing the appropriate unitary transformation and auxiliary particles.

     

Quantum Dialogue by Using Non-Symmetric Quantum Channel

A protocol for quantum dialogue is proposed to exchange directly the communicator＇s secret messages by using a three-dimensional Bell state and a two-dimensional Bell state as quantum channel with quantum superdence coding, local collective unitary operations, and entanglement swapping. In this protocol, during the process of trans- mission of particles, the transmitted particles do not carry any secret messages and are transmitted only one time. The protocol has higher source capacity than protocols using symmetric two-dimensional states. The security is ensured by the unitary operations randomly performed on all checking groups before the particle sequence is transmitted and the application of entanglement swapping.     

Channel parameters-independent multi-hop nondestructive teleportation

A multi-hop nondestructive teleportation scheme independent of channel parameters based on Bell pairs is presented,where the coefficients of the quantum channel are unknown to all the communication nodes.With Bell measurement and channel matching technology the unknown channel parameters can be eliminated probabilistically with the help of the intermediate nodes.Then the source node Alice can teleport an unknown state to the remote destination node Bob.In our scheme the teleportation is generalized first to the scenario independent of channel parameters,which makes the requirement of quantum channel reduced.Our scheme still preserves the initial unknown state even if this teleportation fails.Moreover,performance analysis shows that our scheme has a higher communication efficiency.     

Experimental realization of quantum controlled teleportation of arbitrary two-qubit state via a five-qubit entangled state

Quantum controlled teleportation is the transmission of the quantum state under the supervision of a third party. This paper presents the theoretical and experimental results of an arbitrary two-qubit quantum controlled teleportation scheme, in which the sender Alice only needs to perform two Bell state measurements and the receiver Bob can perform an appropriate unitary operation to reconstruct the arbitrary two-qubit states under the control of the supervisor Charlie. The operation process of the scheme is verified on the IBM quantum experience platform, and the accuracy of the transmitted quantum state is further checked by performing quantum state tomography. Meanwhile, a good fidelity is obtained by using the theoretical density matrix and the experimental density matrix. A sequence of photonic states is introduced to analyze the possible intercept-replace-resend, intercept-measure-resend, and entanglement-measure-resend attacks on this scheme. The results proved that our scheme is highly secure.     

Teleportations of Mixed States and Multipartite Quantum States

In this paper, we propose a protocol to deterministically teleport an unknown mixed state of qubit by utilizing a maximally bipartite entangled state of qubits as quantum channel. Ira non-maximally entangled bipartite pure state is employed as quantum channel, the unknown mixed quantum state of qubit can be teleported with 1 -√ 1- C^2 probability, where C is the concurrence of the quantum channel. The protocol can also be generalized to teleport a mixed state of qudit or a multipartite mixed state. More important purpose is that, on the basis of the protocol, the teleportation of an arbitrary multipartite （pure or mixed） quantum state can be decomposed into the teleportation of each subsystem by employing separate entangled states as quantum channels. In the case of deterministic teleportation, Bob only needs to perform unitary transformations on his single particles in order to recover the initial teleported multipartite quantum state.     

控制的量子隐形传态和控制的量子安全直接通信

我们提出了一个控制的量子隐形传态方案。在这方案中，发送方Alice 在监督者Charlie的控制下以他们分享的三粒子纠缠态作为量子通道将二能级粒子未知态的量子信息忠实的传给了遥远的接受方Bob。我们还提出了借助此传态的控制的量子安全直接通信方案。在保证量子通道安全的情况下， Alice直接将秘密信息编码在粒子态序列上，并在Charlie控制下用此传态方法传给Bob。Bob可通过测量他的量子位读出编码信息。由于没有带秘密信息的量子位在Alice 和Bob之间传送，只要量子通道安全， 这种通信不会泄露给窃听者任何信息， 是绝对安全的。这个方案的的特征是双方通信需得到第三方的许可。     

利用大失谐Jaynes-Cummings模型实现原子的隐形传态

提出了一个未知原子的隐形传态方案,它是通过原子与腔场大失谐相互作用实现的.方案中,两原子缠结的EPR态作为联系发送者与接收者之间的量子信息通道,将欲传送的未知原子和EPR态中的一个原子依次注入到初始制备于相干态 |α>的腔场,然后分别对两原子和腔场进行联合测量,通过经典信息通道将测量结果传递给接收者.这样,接收者只要对EPR的另一个原子执行相应的幺正操作就能重构未知原子态.